Heat exchanger and heat exchange method

ABSTRACT

A heat exchanger includes a channel structure including a first substrate in which a first channel is arrayed, and a second substrate stacked on the first substrate, in which a second channel is arrayed. The first channel has an effective area overlapping a range where the second channel is provided, when viewed in a lamination direction of the first and second substrates. The effective area includes a standard heat transfer channel part including a high temperature end, and a high heat transfer channel part including a low temperature end, which is a part of the effective area other than the standard heat transfer channel part. The high heat transfer channel part has a bent shape so that a channel length thereof per unit distance of an end-to-end distance thereof is greater than a channel length of the standard heat transfer channel part per unit distance of an end-to-end distance thereof.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a heat exchanger and a heat exchangemethod.

Description of the Related Art

Conventionally, a stacked-type heat exchanger has been known as one kindof a heat exchanger having excellent heat exchanger performance. Thisstacked-type heat exchanger includes a stacked body obtained by stackinga plurality of substrates in each of which a plurality of microchannelsare arrayed. This heat exchanger is configured so that heat exchange isperformed between fluid flowing through microchannels arrayed in onesubstrate and fluid flowing through microchannels arrayed in anothersubstrate adjacent to the foregoing substrate. JP 2010-286229 Adiscloses one example of such a stacked-type heat exchanger.

The stacked-type heat exchanger disclosed in JP 2010-286229 A includes astacked body in which a high temperature part layer and a lowtemperature part layer are stacked with a partition wall beinginterposed therebetween. In the high temperature part layer, a pluralityof microchannels through which high temperature fluid is caused to floware arrayed, and in the low temperature part layer, a plurality ofmicrochannels through which low temperature fluid is caused to flow arearrayed. This heat exchanger has a configuration in which a straightchannel is provided in a fluid distributing part, whereas a corrugatedchannel having higher heat transmission and causing greater pressuredrop is provided in a heat transfer part, so that the heat exchanger ismade compact.

In the heat exchanger of JP-2010-286229-A, priority is given to heattransfer performance in order to make the heat exchanger compact, butthis leads to a risk that an excessive pressure drop is caused by thecorrugated channel of the microchannel, that is, an excessive pressureloss occurs.

An object of the present invention is to improve heat transferperformance of a heat exchanger, and prevent excessive pressure lossfrom occurring, while preventing the increase in the size of the heatexchanger.

A heat exchanger according to the present invention is a heat exchangerthat causes a plurality of fluids to flow therethrough so as to causeheat exchange to occur between the fluids. The heat exchanger includes achannel structure that includes: a first layer in which a first channelthat is a microchannel through which one fluid is caused to flow isarrayed; and a second layer stacked on the first layer, in which asecond channel that is a microchannel through which another fluid iscaused to flow is arrayed, the other fluid being a fluid different fromthe one fluid. The first channel has an effective area that overlaps arange where the second channel in the second layer is provided, whenviewed in a direction in which the first layer and the second layer arestacked. The effective area includes: a standard heat transfer channelpart that includes a high temperature end that is one of ends of theeffective area; and a high heat transfer channel part that is equivalentto a part of the effective area other than the standard heat transferchannel part, the high heat transfer channel part including a lowtemperature end that is an end of the effective area on a side oppositeto the high temperature end and through which the one fluid having atemperature lower than a temperature of the one fluid flowing at thehigh temperature end. The high heat transfer channel part has a channelshape bent in such a manner that a channel length thereof per unitdistance of an end-to-end distance thereof is greater than a channellength of the standard heat transfer channel part per unit distance ofan end-to-end distance thereof.

In this heat exchanger, the effective area of the first channel includesthe high heat transfer channel part, and this high heat transfer channelpart has a channel shape bent in such a manner that the channel lengththereof per unit distance of the end-to-end distance thereof is greaterthan the channel length of the standard heat transfer channel part ofthe effective area per unit distance of the end-to-end distance thereof.In other words, the high heat transfer channel part has a greater numberof bent portions than the standard heat transfer channel part, oralternatively, has a bent portion having a greater degree of bendingthan the standard heat transfer channel part. This makes it possible toimprove heat transfer performance owing to the fluid turbulence at thebent portions of the high heat transfer channel part. Further, with thehigh heat transfer channel part formed in the bent channel shape, whichsuppresses the increase in the end-to-end distance thereof, the increasein the size of the heat exchanger can be prevented. Accordingly, theincrease in the size of this heat exchanger can be prevented, and theheat transfer performance thereof can be improved.

Moreover, in this heat exchanger, the standard heat transfer channelpart is a part that includes the high temperature end of the effectivearea, and the high heat transfer channel part is equivalent to a part ofthe effective area other than the standard heat transfer channel part,which includes the low temperature end of the effective area. Theamplitude of the increase in the pressure loss in the effective area ofthe first channel, therefore, can be reduced. More specifically, since apressure loss in a channel is proportional to a flow rate of a fluidflowing through the channel, the configuration in which a part of theeffective area through which the first fluid having a low temperatureand hence having a relatively higher density flows and that includes thelow temperature end at which the first fluid comes to have a smallerflow rate is the high heat transfer channel part, and the other part ofthe effective area that includes the high temperature end is thestandard heat transfer channel part, enables to reduce the amplitude ofthe increase in the pressure loss, even if the pressure loss isincreased by the high heat transfer channel part thus bent. It istherefore possible to prevent excessive pressure loss from occurring inthe first channels. Still further, since the first fluid has a higherdensity and hence has a smaller flow rate at and near the lowtemperature end of the effective area as described above, the heattransfer performance is relatively low in this part. In this heatexchanger, however, since the high heat transfer channel part includesthe low temperature end, the relatively low heat transfer performance atand near the low temperature end can be improved by the high heattransfer channel part. This makes it possible to achieve the high heattransfer performance with a good balance in the entirety of theeffective area of the first channel.

In the above-described heat exchanger, preferably, the standard heattransfer channel part is a straight channel, and the high heat transferchannel part is a wavy type channel.

With this configuration in which the standard heat transfer channel partis a straight channel, the pressure loss in the standard heat transferchannel part can be reduced, as compared with a case where the standardheat transfer channel part has a curved channel shape or a bent channelshape. To this extent, the increase in the pressure loss in theeffective area can be suppressed.

In this case, preferably, the high heat transfer channel part meandersin such a manner as being deflected to both sides with respect to acenter line that is a straight line, and the end-to-end distance of thehigh heat transfer channel part in a direction along the center line is60% or less of an end-to-end distance of the effective area.

With this configuration, the pressure loss in the effective area can besuppressed to less than twice the pressure loss in the effective area ina case where the entirety of the effective area is a straight channel.In view of practical application of the heat exchanger, if the pressureloss in the effective area of the first channel increases to twice ormore the value of pressure loss in an effective area in a case where theentire effective area is a straight channel, it is difficult to use afirst channel having such an effective area. With the presentconfiguration, the increase in the pressure loss can be suppressed toless than twice as described above, and hence, a first channel that issufficiently able to be adopted for practical application in view ofpressure loss can be obtained.

Further, in this case, the end-to-end distance of the high heat transferchannel part in a direction along the center line is preferably 10% ormore of the end-to-end distance of the effective area.

With this configuration, a heat transfer area that can sufficientlycompensate the reductions in the heat transfer performance that aregenerally expected due to dirt and/or fluid conditions in the effectivearea can be ensured in the effective area.

Still further, in the configuration in which the standard heat transferchannel part is a straight channel and the high heat transfer channelpart is a wavy type channel, preferably, the high heat transfer channelpart meanders in such a manner as being deflected to both sides withrespect to a center line that is a straight line, and the end-to-enddistance of the high heat transfer channel part in a direction along thecenter line is smaller than the end-to-end distance of the standard heattransfer channel part.

With this configuration, the improvement of the heat transferperformance and the prevention of excessive increase in the pressureloss can be achieved with a good balance, while the increase in the sizeof the heat exchanger can be prevented.

A heat exchange method according to the present invention includescausing one fluid to flow through the first channel in theabove-described heat exchanger from the standard heat transfer channelpart toward the high heat transfer channel part, and at the same time,causing a refrigerant as another fluid to flow through the secondchannel in the heat exchanger, so as to cause heat exchange to occurbetween the one fluid and the refrigerant.

Further, a heat exchange method according to the present inventionincludes causing one fluid to flow through the first channel in theabove-described heat exchanger from the high heat transfer channel parttoward the standard heat transfer channel part, and at the same time,causing a hot medium as another fluid to flow through the second channelof the heat exchanger, so as to cause heat exchange to occur between theone fluid and the hot medium.

As described above, according to the present invention, it is possibleto improve heat transfer performance of a heat exchanger, and preventexcessive pressure loss from occurring, while preventing the increase inthe size of the heat exchanger

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a heat exchanger according toone embodiment of the present invention.

FIG. 2 is a plan view of a first substrate that composes a channelstructure of the heat exchanger illustrated in FIG. 1.

FIG. 3 is a plan view of a second substrate that composes the channelstructure heat exchanger illustrated in FIG. 1.

FIG. 4 is an enlarged view of high heat transfer channel parts of firstchannels.

FIG. 5 is a partial sectional view of the first substrate in which thefirst channels are formed and its surrounding area, in the channelstructure.

FIG. 6 illustrates correlation between a ratio of an end-to-end distanceof a high heat transfer channel part of a first channel to an end-to-enddistance of an effective area of the same and a pressure loss calculatedby simulation.

FIG. 7 illustrates correlation between a ratio of an end-to-end distanceof a high heat transfer channel part of a first channel to an end-to-enddistance of an effective area of the same and a heat transfercoefficient calculated by simulation.

FIG. 8 illustrates correlation between a ratio of an end-to-end distanceof a high heat transfer channel part of a first channel to an end-to-enddistance of an effective area of the same and a ratio of pressure lossto a heat transfer coefficient calculated by simulation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description describes an embodiment of the presentinvention, while referring to the drawings.

FIG. 1 illustrates an overall configuration of a heat exchanger 1according to one embodiment of the present invention. The heat exchanger1 has such a configuration that a first fluid and a second fluid arecaused to exchange heat while flowing through the heat exchanger. Theheat exchanger 1 includes a channel structure 2, a first supply header3, a second supply header 4, a first discharge header 5, and a seconddischarge header 6.

The channel structure 2 is a rectangular parallelepiped structure thatincludes, in the inside thereof, a multiplicity of first channels 21(see FIG. 2) that are microchannels through which the first fluid iscaused to flow, and a multiplicity of second channels 22 (see FIG. 3)that are microchannels through which the second fluid is caused to flow.The channel structure 2 includes a plurality of first substrates 11 ineach of which a plurality of the first channels 21 are arrayed, and aplurality of second substrates 12 in each of which a plurality of thesecond channels 22 are arrayed. The first substrate 11 is one example ofthe first layer in the present invention, and the second substrate 12 isone example of the second layer in the present invention.

Each of the first substrates 11 and the second substrates 12 is a flatplate in a rectangular shape when viewed from one side in the thicknessdirection thereof, and is formed with, for example, a stainless steelplate. In the channel structure 2, the first substrates 11 and thesecond substrates 12 are alternately stacked and bonded to one another.This results in that, in the channel structure 2, the first channels 21arrayed in the first substrate 11, and the second channels 22 arrayed inthe second substrate 12 are arrayed alternately in a laminationdirection where the substrate 11 and the substrate 12 are stacked. Thechannel structure 2 has four lateral faces that are formed with endfaces that correspond to four sides of each of the substrates 11, 12.

On one of plate surfaces of each first substrate 11, as illustrated inFIG. 2, a plurality of first grooves 23 that form a plurality of thefirst channels 21 are formed. Each of the first grooves 23 is formed byetching, and has an arc-shaped cross section, as illustrated in FIG. 5.The openings of the first grooves 23 on one of plate surfaces of thefirst substrate 11 are sealed by the second substrate 12 stacked on theplate surface of the first substrate 11, whereby a plurality of thefirst channels 21 arrayed on the one plate surface are formed.

Each first channel 21 extends approximately in the longitudinaldirection of the first substrate 11. In the present embodiment, thechannel structure 2 is arranged in such a posture that a standard heattransfer channel part 25 to be described below of each first channel 21extends in an up-to-down direction. In other words, the channelstructure 2 is arranged in such a posture that the longitudinaldirection of each of the substrates 11, 12 coincides with the verticaldirection.

Each first channel 21 has, at one end thereof, an introduction port 21 a(see FIG. 2) through which the first fluid is introduced, and at an endon a side opposite to the introduction port 21 a, an outflow port 21 bthrough which the first fluid having flown through the first channel 21is allowed to flow out. The introduction ports 21 a are open on alateral face of the channel structure 2, which is formed with end faceson one side in the longitudinal direction of the substrates 11, 12, andthe outflow ports 21 b are open on a lateral face on a side opposite tothe side of the lateral face where the introduction ports 21 a are open.In other words, the introduction ports 21 a are open on a lateral faceof the channel structure 2 that faces downward, and the outflow ports 21b are open on a lateral face of the channel structure 2 that facesupward.

In the present embodiment, to the first channels 21, a first fluidhaving a low temperature is introduced from the introduction ports 21 a,respectively, and the first fluid thus introduced thereto, as flowingtoward the outflow port 21 b, exchanges heat with the high temperaturesecond fluid flowing through the second channels 22, whereby thetemperature of the first fluid rises. In the present embodiment,therefore, in a part closer to the introduction port 21 a in each firstchannel 21, the first fluid flowing there has a lower temperature, andin a part closer to the outflow port 21 b in each first channel 21, thefirst fluid flowing there has a relatively higher temperature.

The first channel 21 has an effective area 24 (see FIG. 2) thatcontributes to heat exchange between the first fluid flowing through thefirst channel 21 and the second fluid flowing through the second channel22. The effective area 24 is an area of the first channel 21 thatoverlaps a range where the second channels 22 are provided in the secondsubstrate 12 when viewed in the lamination direction of the substrates11, 12. More specifically, when viewed in the lamination direction ofthe substrates 11, 12, a small area at and near the introduction ports21 a and a small area at and near the outflow ports 21 b in the firstchannels 21 do not overlap the range where the second channels 22 areprovided in the second substrate 12, and hence, the effective area 24 isequivalent to an area of the first channel 21 from which these smallareas are excluded.

The effective area 24 is composed of the standard heat transfer channelpart 25 and the high heat transfer channel part 26, as illustrated inFIG. 2.

The standard heat transfer channel parts 25, in the present embodiment,are straightly extending channels, that is, straight channels, andextend in the longitudinal direction of the first substrate 11. Thestandard heat transfer channel part 25 includes a high temperature end24 a, which is one end of the effective area 24. The high temperatureend 24 a is a part through which the first fluid flows that has a highertemperature as compared with the first fluid flowing through a lowtemperature end 24 b to be described below. More specifically, the hightemperature end 24 a is a part through which the first fluid flows thathas the highest temperature in the effective area 24. The standard heattransfer channel part 25 is equivalent to a part of the effective area24 having a predetermined length from the high temperature end 24 atoward the introduction port 21 a.

The high heat transfer channel part 26 is equivalent to a part of theeffective area 24 other than the standard heat transfer channel part 25.The high heat transfer channel part 26 includes a low temperature end 24b that is an end of the effective area 24 on a side opposite to the hightemperature end 24 a. The low temperature end 24 b is a part throughwhich the first fluid flows that has a lower temperature as comparedwith the first fluid flowing through the high temperature end 24 a. Morespecifically, the low temperature end 24 b is a part through which thefirst fluid flows that has the lowest temperature in the effective area24. The high heat transfer channel part 26 is equivalent to a part ofthe effective area 24 having a predetermined length from the lowtemperature end 24 b toward the high temperature end 24 a.

Each high heat transfer channel part 26 has a channel shape bent in sucha manner that a channel length thereof per unit distance of theend-to-end distance thereof is greater than a channel length of thestandard heat transfer channel part 25 per unit distance of theend-to-end distance thereof. More specifically, each high heat transferchannel part 26 is a wavy type channel that meanders in such a manner asbeing deflected to both sides with respect to, as the center, a meandercenter line 27 that is a straight line. The meander center line 27 is aline extending in the same direction as the direction of the center lineof the channel width of the standard heat transfer channel part 25.Further, the “end-to-end distance of the high heat transfer channel part26” refers to an end-to-end distance of the high heat transfer channelpart 26 in the direction along the meander center line 27. Stillfurther, the channel length of the high heat transfer channel part 26per unit distance of the end-to-end distance thereof is equivalent to avalue obtained by diving the entire channel length of the high heattransfer channel part 26 by the end-to-end distance of the high heattransfer channel part 26. Sill further, the end-to-end distance of thestandard heat transfer channel part 25 is equivalent to the end-to-endstraight distance of the standard heat transfer channel part 25. Stillfurther, the channel length of the standard heat transfer channel part25 per unit distance of the end-to-end distance thereof is equivalent toa value obtained by dividing the entire channel length of the standardheat transfer channel part 25 by the end-to-end distance of the standardheat transfer channel part 25.

The high heat transfer channel part 26, as illustrated in FIG. 4,includes a plurality of first straight parts 26 a, a plurality of secondstraight parts 26 b, and a plurality of corner parts 26C.

The first straight part 26 a is a part that straightly extends from aside of one end of the high heat transfer channel part 26 toward a sideof the other end thereof, intersecting with the meander center line 27obliquely from one side thereto to the other side thereto. The secondstraight part 26 b is a part that straightly extends from a side of oneend of the high heat transfer channel part 26 toward a side of the otherend thereof, intersecting with the meander center line 27 obliquely fromthe above-described other side to the above-described one side. Thefirst straight parts 26 a and the second straight parts 26 b arealternately repeatedly arranged from a side of one end of the high heattransfer channel part 26 toward a side of the other end thereof.

The channel width center line of each of the first straight parts 26 ais tilted by an angle D with respect to the meander center line 27. Thechannel width center line of each of the second straight parts 26 b istilted with respect to the meander center line 27, in an orientationopposite to the orientation where the center line of the first straightpart 26 a is tilted, by the same angle as the tilt angle of the centerline of the first straight part 26 a, that is, the angle D. Each cornerpart 26C is formed in a rounded shape, and connects an end of the firststraight part 26 a and an end of the second straight part 26 b that areopposite each other.

By forming each of the first straight parts 26 a, each of the secondstraight parts 26 b, and each of the corner parts 26C as is describedabove, the high heat transfer channel part 26 is formed in a zig-zagshape with respect to the meander center line 27, and in an overallconfiguration, extends along the meander center line 27.

The end-to-end distance of the high heat transfer channel part 26 in thedirection along the meander center line 27 is given as “L_(x)”, apressure loss of the effective area 24 is given as “f_(x)”, and a filmcoefficient of heat transfer of the first fluid in the effective area 24(hereinafter referred to simply as the “heat transfer coefficient forthe effective area 24) is given as “j_(x)”. Then, the end-to-enddistance L_(x) of the high heat transfer channel part 26, the pressureloss f_(x) of the effective area 24, and the heat transfer coefficientj_(x) satisfy the following relational expression (1):

(α×f _(x) /j _(x))<A×L _(x)  (1)

In the relational expression (1), a is a correction coefficient definedby the following relational expression (2):

α×f ₀ /j ₀=1  (2)

In this relational expression (2), “f₀” represents a pressure loss of aneffective area in a case where the entirety of the effective area 24 iscomposed of a straight channel such as the standard heat transferchannel part 25, and “j₀” represents a heat transfer coefficient for aneffective area in a case where the entirety of the effective area 24 iscomposed of a straight channel such as the standard heat transferchannel part 25.

Further, in the above-described relational expression (1), “A”represents a value defined by the following relational expression (3):

A=(α×f _(all) /j _(all))/L _(all)  (3)

In this relational expression (3), “f_(all)” represents a pressure lossof an effective area in a case where the entirety of the effective area24 is formed in a bent channel shape like the high heat transfer channelpart 26, and “j_(all)” represents a heat transfer coefficient of aneffective area in a case where the entirety of the effective area 24 isformed in a bent channel shape like the high heat transfer channel part26. Further, “L_(all)” represents an end-to-end distance of theeffective area 24, and is equivalent to the distance between the lowtemperature end 24 b and the high temperature end 24 a. The end-to-enddistance of the effective area 24, more specifically, refers to theend-to-end distance of the effective area 24 in a direction along thechannel width center line of the standard heat transfer channel part 25and the meander center line 27 of the high heat transfer channel part26.

In the present embodiment, the end-to-end distance of the high heattransfer channel part 26 in the direction along the meander center line27 is set to 10% or more of the end-to-end distance of the effectivearea 24 and 60% or less of the end-to-end distance of the effective area24. In addition, preferably, the end-to-end distance of the high heattransfer channel parts 26 in the direction along the meander centerlines 27 is set to be a distance smaller than the end-to-end distance ofthe standard heat transfer channel parts 25, in other words, a distancesmaller than 50% of the end-to-end distance of the effective area 24.

Further, each first channel 21 includes an introduction channel part 29and an outflow channel part 30, as illustrated in FIG. 2.

The introduction channel part 29 is a small part at and near theintroduction port 21 a of the first channel 21, and is equivalent to apart of the first channel 21 that does not overlap a range where thesecond channels 22 are provided on the second substrate 12. In otherwords, the introduction channel part 29 is equivalent to a part of thefirst channel 21 positioned on the introduction port 21 a side withrespect to the effective area 24. The introduction channel part 29straightly extends from the introduction port 21 a, and is connected tothe high heat transfer channel part 26. The first fluid supplied to theintroduction port 21 a passes through the introduction channel part 29,and flows to the high heat transfer channel part 26.

The outflow channel part 30 is a small part at and near the outflow port21 b of the first channel 21, and is equivalent to a part that does notoverlap a range where the second channels 22 are provided on the secondsubstrate 12. In other words, the outflow channel part 30 is equivalentto a part of the first channel 21 positioned on the outflow port 21 bside with respect to the effective area 24. The outflow channel part 30straightly extends in the same direction as the standard heat transferchannel part 25 on a line of extension of the standard heat transferchannel part 25, and is connected to the outflow port 21 b. The firstfluid that has flown through the standard heat transfer channel part 25passes through the outflow channel part 30, and flows out of the outflowport 21 b.

On one of the plate surfaces of each second substrate 12 (see FIG. 3), aplurality of second grooves 32 that form the second channels 22 areformed by etching. FIG. 3 principally illustrates an outer shape of acollective configuration of the second grooves 32 formed on the secondsubstrate 12, and the illustration of each second groove 32 and eachsecond channel 22 is omitted, except for parts thereof at and near theupstream ends thereof and parts thereof at and near the downstream endsthereof. The opening of each second groove 32 on one of plate surfacesof the second substrate 12 is sealed by the first substrate 11 stackedon the plate surface, whereby a plurality of the second channels 22arrayed on the one of the plate surfaces are formed.

In the present embodiment, in each second channel 22, a part thatstraightly extends from one side to the other side in the transversedirection of the second substrate 12, and a part that is turned backtherefrom and straightly extends from the above-described other side tothe above-described one side, are repeatedly provided, so that thesecond channel 22 as a whole is in a largely wavy type shape.

Each second channel 22 has, at one end thereof, an introduction port 22a through which the second fluid is introduced, and at an end on a sideopposite to the introduction port 22 a, an outflow port 22 b throughwhich the second fluid having passed through the second channel 22 isallowed to flow out.

The introduction ports 22 a are open on a lateral face of the channelstructure 2, which is formed with end faces on one side in thetransverse direction of the substrates 11, 12. In the presentembodiment, the introduction ports 22 a are open on a lateral face ofthe channel structure 2 that faces to one side in the horizontaldirection, and are arranged at and near an upper end art of the lateralface. In other words, the introduction ports 22 a are arranged closer tothe outflow ports 21 b of the first channels 21.

The outflow ports 22 b are open on a lateral face of the channelstructure 2 on a side opposite to the lateral face of the channelstructure 2 where the introduction ports 22 a are open. In the presentembodiment, the outflow ports 22 b are arranged at and near a lower endpart of the lateral face of the channel structure 2 where the outflowports 22 b are open. In other words, the outflow ports 22 b are arrangedcloser to the introduction ports 21 a of the first channel 21.

In the present embodiment, to the second channels 22, the second fluidhaving a temperature higher than the first fluid is introduced from theintroduction ports 22 a, and the second fluid thus introduced thereto,as flowing to the outflow port 22 b, exchanges heat with the first fluidhaving a low temperature flowing through the first channels 21, wherebythe temperature of the second fluid drops.

The first supply header 3 (see FIGS. 1 and 2) distributes and suppliesthe first fluid to all of the respective introduction ports 21 a of thefirst channels 21 provided in the channel structure 2. The first supplyheader 3 is attached to one of the lateral faces of the channelstructure 2 where the introduction ports 21 a of the first channels 21are open. The first supply header 3 collectively covers all of theintroduction ports 21 a that are open on the lateral face of the channelstructure 2 to which the first supply header 3 is attached. This allowsthe space in the first supply header 3 to communicate with eachintroduction port 21 a. To the first supply header 3, a supply pipe (notillustrated) is connected, so that the first fluid supplied through thesupply pipe to the first supply header 3 is distributed from the spacein the first supply header 3 to the introduction ports 21 a.

The first discharge header 5 (see FIGS. 1 and 2) receives the firstfluid flowing out of all of the outflow ports 21 b of the first channels21 provided in the channel structure 2. The first discharge header 5 isattached to one of the lateral faces of the channel structure 2 wherethe outflow ports 21 b of the first channels 21 are open. The firstdischarge header 5 collectively covers all of the outflow ports 21 bthat are open on the lateral face of the channel structure 2 to whichthe first discharge header 5 is attached. This allows the space in thefirst discharge header 5 to communicate with each outflow port 21 b. Tothe first discharge header 5, a discharge pipe (not illustrated) isconnected, so that the first fluid having flown out of each outflow port21 b to the space in the first discharge header 5 is discharged throughthis discharge pipe.

The second supply header 4 (see FIGS. 1 and 3) distributes and suppliesthe second fluid to all of the introduction ports 22 a of the secondchannels 22 provided in the channel structure 2. The second supplyheader 4 is attached to the one of the lateral faces of the channelstructure 2 where the introduction ports 22 a of the second channels 22are open, and collectively covers all of the introduction ports 22 athat are open on the lateral face. This allows the space in the secondsupply header 4 to communicate with each introduction port 22 a. To thesecond supply header 4, a supply pipe (not illustrated) is connected, sothat the second fluid having been supplied through the supply pipe tothe second supply header 4 is distributed from the space in the secondsupply header 4 to the introduction ports 22 a.

The second discharge header 6 (see FIGS. 1 and 3) receives the secondfluid flowing out of all of the outflow ports 22 b of the secondchannels 22 provided in the channel structure 2. The second dischargeheader 6 is attached to one of the lateral faces of the channelstructure 2 where the outflow ports 22 b of the second channels 22 areopen, and collectively covers all of the outflow ports 22 b that areopen on the lateral face to which the second discharge header 6 isattached. This allows the space in the second discharge header 6 tocommunicate with each outflow port 22 b. To the second discharge header6, a discharge pipe (not illustrated) is connected, so that the secondfluid having flown out of the each outflow port 22 b to the space in thesecond discharge header 6 is discharged through this discharge pipe.

In the present embodiment, a heat exchange method for heat exchangebetween the first fluid and the second fluid is performed by using theheat exchanger 1 having a configuration as described above. For example,in order to raise the temperature of the first fluid, a heat exchangemethod for heat exchange between the first fluid and a hot medium (heatmedium) as the second fluid having a temperature higher than that of thefirst fluid is performed.

More specifically, the first fluid is supplied through the supply pipeto the first supply header 3 so that the first fluid is supplied fromthe first supply header 3 to each first channel 21, whereby the firstfluid is caused to flow through each first channel 21 from the high heattransfer channel part 26 toward the standard heat transfer channel part25. On the other hand, the hot medium as the second fluid is suppliedthrough the supply pipe to the second supply header 4 so that the hotmedium is supplied from the second supply header 4 to each secondchannel 22, whereby the hot medium is caused to flow through each secondchannel 22. By doing so, heat exchange is caused to occur between thefirst fluid flowing through the first channels 21 and the hot mediumflowing through the second channels 22, whereby the temperature of thefirst fluid is raised.

In the heat exchanger 1 according to the present embodiment, theeffective area 24 of the first channel 21 includes the high heattransfer channel part 26, and this high heat transfer channel part 26 isa wavy type channel that is bent in such a manner that the channellength of the high heat transfer channel part 26 per unit distance ofthe end-to-end distance thereof is greater than the channel length ofthe standard heat transfer channel part 25 per unit distance of theend-to-end distance thereof. This causes fluid turbulence at bentportions of the high heat transfer channel part 26, which improves heattransfer performance.

Further, since the bent channel shape of the high heat transfer channelpart 26 makes it possible to suppress the increase in the end-to-enddistance thereof, in the present embodiment, it is possible to preventthe increase in the size of the heat exchanger 1. In the presentembodiment, therefore, it is possible to improve the heat transferperformance while preventing the increase in the size of the heatexchanger 1.

Still further, in the heat exchanger 1 according to the presentembodiment, the standard heat transfer channel part 25 is a part thatincludes the high temperature end 24 a of the effective area 24, and thehigh heat transfer channel part 26 is a part that is equivalent to apart of the effective area 24 other than the standard heat transferchannel part 25 and includes the low temperature end 24 b of theeffective area 24. This makes it possible to reduce the amplitude of theincrease in the pressure loss in the effective area 24 of the firstchannel 21. In other words, since a pressure loss of a channel isproportional to a flow rate of a fluid flowing through the channel, theconfiguration in which a part of the effective area 24 through which thefirst fluid having a low temperature and hence having a relativelyhigher density flows and that includes the low temperature end 24 b atwhich the first fluid comes to have a smaller flow rate is formed withthe high heat transfer channel part 26, and the other part of theeffective area 24 that includes the high temperature end 24 a is thestandard heat transfer channel part 25, enables to reduce the amplitudeof the increase in the pressure loss, even if the pressure loss isincreased by the high heat transfer channel part 26 thus bent. It istherefore possible to prevent excessive pressure loss from occurring inthe first channels 21.

Still further, since the first fluid has a higher density and hence hasa smaller flow rate at and near the low temperature end of the effectivearea as described above, the heat transfer performance is relatively lowin this part. In the present embodiment, however, since the high heattransfer channel part 26 includes the low temperature end 24 b, therelatively low heat transfer performance at and near the low temperatureend 24 b can be improved by the high heat transfer channel part 26. Thismakes it possible to achieve the high heat transfer performance with agood balance in the entirety of the effective areas 24 of the firstchannels 21.

Still further, in the present embodiment, since the high heat transferchannel part 26 is a wavy type channel, it is possible to increase thechannel length of the high heat transfer channel part 26 so as toincrease the heat transfer area, while suppressing the increase in theend-to-end distance of the high heat transfer channel part 26, ascompared with a configuration in which a high heat transfer channel partis simply curved. In other words, it is possible to improve the heattransfer performance more effectively, while suppressing the increase inthe end-to-end distance of the high heat transfer channel part 26. Stillfurther, since the standard heat transfer channel part 25 is a straightchannel, the pressure loss in the standard heat transfer channel part 25can be reduced, as compared with a case where the standard heat transferchannel part has a curved channel shape or a bent channel shape. To thisextent, the increase in the pressure loss in the effective area 24 canbe suppressed.

Still further, in the present embodiment, since the end-to-end distanceof the high heat transfer channel part 26 in the direction along themeander center line 27 is set to 60% or less of the end-to-end distanceof the effective area 24, the pressure loss in the effective area 24 canbe suppressed to less than twice the pressure loss in an effective areain a case where the entirety of the effective area is a straightchannel, which sufficiently satisfies the requirements regarding thepressure loss of the heat exchanger for practical application.

Still further, in the present embodiment, the end-to-end distance of thehigh heat transfer channel part 26 in the direction along the meandercenter line 27 is set to 10% or more of the end-to-end distance of theeffective area 24.

In a heat exchanger, generally, a heat transfer area is set with amargin with respect to the theoretical value of a heat transfer areadetermined by computation, with consideration given to a possibilitythat the heat transfer performance decreases due to dirt (deposit) inchannels and/or fluid conditions such as temperature and pressure offluid. In this case, generally, a heat transfer area about 5% to 10%larger than the theoretical value of the heat transfer area is set. Incontrast, with such a setting that the end-to-end distance of the highheat transfer channel part 26 in the direction along the meander centerline 27 is set to 10% or more of the end-to-end distance of theeffective area 24, as is the case with the present embodiment, a heattransfer area that can sufficiently compensate the reductions in theheat transfer performance that are generally expected due to dirt and/orfluid conditions in the effective area 24 can be ensured in theeffective area 24.

Still further, in a more preferable configuration of the presentembodiment, the end-to-end distance of the high heat transfer channelpart 26 in the direction along the meander center line 27 is set to besmaller than the end-to-end distance of the standard heat transferchannel part 25. In this case, the improvement of the heat transferperformance and the prevention of excessive increase in the pressureloss can be achieved with a good balance, while the increase in the sizeof the heat exchanger 1 can be prevented.

More specifically, if it is assumed that the end-to-end distance of thehigh heat transfer channel part 26 is greater than the end-to-enddistance of the standard heat transfer channel part 25, the effect ofimprovement of the heat transfer performance owing to the high heattransfer channel parts 26 would increase, but on the other hand, theamplitude of the increase in the pressure loss would be expanded. Tosuppress the increase in the pressure loss, for example, the number ofthe first channels 21 provided in the channel structure 2 may beincreased, but this necessarily increases the size of the channelstructure 2. In other words, this necessarily increases the size of theheat exchanger 1. In contrast, with the configuration in which theend-to-end distance of the high heat transfer channel part 26 is smallerthan the end-to-end distance of the standard heat transfer channel part25, the improvement of the heat transfer performance and the preventionof excessive increase in the pressure loss can be achieved with a goodbalance, which results in that the increase in the size of the heatexchanger 1 can be prevented.

The following description describes results of simulation performed inorder to examine the effects achieved by the heat exchanger 1 of thepresent embodiment, that is, the effects achieved by the configurationin which parts of the effective areas 24 that are other than thestandard heat transfer channel parts 25 and that include the lowtemperature ends 24 b of the effective areas 24 are the high heattransfer channel parts 26.

First of all, as examples corresponding to the present embodiment,Examples 1 to 4 were set in which only an end-to-end distance of thehigh heat transfer channel part 26 as a wavy type channel, that is, anend-to-end distance of the high heat transfer channel part 26 in thedirection along the meander center line 27, was varied, as follows.

Example 1

The end-to-end distance of each high heat transfer channel part 26 wasset to a distance equivalent to 20% of the end-to-end distance of theeffective area 24, and a part of each effective area 24 other than thehigh heat transfer channel part 26 was the standard heat transferchannel part 25, which was a straight channel.

Example 2

The end-to-end distance of each high heat transfer channel part 26 wasset to a distance equivalent to 40% of the end-to-end distance of theeffective area 24, and a part of each effective area 24 other than thehigh heat transfer channel part 26 was the standard heat transferchannel part 25, which was a straight channel.

Example 3

The end-to-end distance of each high heat transfer channel part 26 wasset to a distance equivalent to 60% of the end-to-end distance of theeffective area 24, and a part of each effective area 24 other than thehigh heat transfer channel part 26 was the standard heat transferchannel part 25, which was a straight channel.

Example 4

The end-to-end distance of each high heat transfer channel part 26 wasset to a distance equivalent to 80% of the end-to-end distance of theeffective area 24, and a part of each effective area 24 other than thehigh heat transfer channel part 26 was the standard heat transferchannel part 25, which was a straight channel.

In addition, as comparative examples for comparison of effects with theexamples, Comparative Examples 1 to 6 described below were set.

Comparative Example 1

The entirety of each effective area 24 was a straight channel.

Comparative Example 2

A part of each effective area 24 ranging from the high temperature end24 a toward the low temperature end 24 b which was equivalent to 20% ofthe end-to-end distance of the effective area 24, was a wavy typechannel corresponding to the high heat transfer channel part 26, and theother part of each effective area 24 was a straight channel.

Comparative Example 3

A part of each effective area 24 ranging from the high temperature end24 a toward the low temperature end 24 b, which was equivalent to 40% ofthe end-to-end distance of the effective area 24, was a wavy typechannel corresponding to the high heat transfer channel part 26, and theother part of each effective area 24 was a straight channel.

Comparative Example 4

A part of each effective area 24 ranging from the high temperature end24 a toward the low temperature end 24 b, which was equivalent to 60% ofthe end-to-end distance of the effective area 24, was a wavy typechannel corresponding to the high heat transfer channel part 26, and theother part of each effective area 24 was a straight channel.

Comparative Example 5

A part of each effective area 24 ranging from the high temperature end24 a toward the low temperature end 24 b, which was equivalent to 80% ofthe end-to-end distance of the effective area 24, was a wavy typechannel corresponding to the high heat transfer channel part 26, and theother part of each effective area 24 was a straight channel.

Comparative Example 6

The entirety of each effective area 24 was a wavy type channelcorresponding to the high heat transfer channel part 26.

As to each of Examples 1 to 4 and Comparative Examples 1 to 6 describedabove, a pressure loss and a heat transfer coefficient in the effectiveareas 24 as a whole were calculated by simulation. Here, the pressureloss and the heat transfer coefficient were calculated, with physicalproperties and flow rates of the fluid flowing through the channels, andother conditions being set to be equal in all of the examples and thecomparative examples.

Table 1 shown below indicates, regarding each of Examples 1 to 4,calculation results of the pressure loss f and the heat transfercoefficient j, and a ratio f/j of a pressure loss f to the heat transfercoefficient j. Further, Table 2 shown below indicates, regarding each ofComparative Examples 1 to 6, calculation results of the pressure loss fand the heat transfer coefficient j, and the ratio f/j of the pressureloss f to the heat transfer coefficient j. In each table shown below,the value of the pressure loss calculated regarding Comparative Example1 is assumed to be 100, and values of the pressure loss calculatedregarding Examples 1 to 4 and Comparative Examples 2 to 6 are expressedas values with respect to the value of the pressure loss of ComparativeExample 1. Besides, in each table shown below, the value of the heattransfer coefficient calculated regarding Comparative Example 1 isassumed to be 100, and values of the heat transfer coefficientcalculated regarding Examples 1 to 4 and Comparative Examples 2 to 6 areexpressed as values with respect to the value of the heat transfercoefficient of Comparative Example 1.

TABLE 1 Example 1 Example 2 Example 3 Example 4 f 128 160 195 234 j 123147 170 191 f/j 104% 109% 115% 123%

TABLE 2 Comparative Comparative Comparative Comparative ComparativeComparative example 1 example 2 example 3 example 4 example 5 example 6f 100 142 181 216 248 276 j 100 120 142 165 188 211 f/j 100% 118% 127%131% 131% 131%

Further, FIG. 6 illustrates, regarding each of Examples 1 to 4 denotedby “E1” to “E4”, and Comparative Examples 1 to 6 denoted by “R1” to“R6”, correlation between the ratio of the end-to-end distance of thehigh heat transfer channel part to the end-to-end distance of theeffective area and the calculated pressure loss f. FIG. 7 illustrates,regarding each of Examples 1 to 4 denoted by “E1” to “E4”, andComparative Examples 1 to 6 denoted by “R1” to “R6”, correlation betweenthe ratio of the end-to-end distance of the high heat transfer channelpart to the end-to-end distance of the effective area and the calculatedheat transfer coefficient j. Still further, FIG. 8 illustrates,regarding each of Examples 1 to 4 denoted by “E1” to “E4”, andComparative Examples 1 to 6 denoted by “R1” to “R6”, correlation betweenthe ratio of the end-to-end distance of the high heat transfer channelpart to the end-to-end distance of the effective area and the calculatedratio f/j of the pressure loss f to the heat transfer coefficient j.

With reference to Tables 1 and 2 as well as FIG. 7, the heat transfercoefficients j are compared between examples having the same end-to-enddistance of the high heat transfer channel part, among E1 to E4 ofExamples 1 to 4 and R2 to R5 of Comparative Examples 2 to 5. Then, it isclear that Examples had slightly greater heat transfer coefficients j ascompared with Comparative Examples. On the other hand, with reference toTables 1 and 2 as well as FIG. 6, the pressure losses f are comparedbetween examples having the same end-to-end distance of the high heattransfer channel part among E1 to E4 of Examples 1 to 4 and R2 to R5 ofComparative Examples 2 to 5. Then, it is clear that Examples hadsignificantly smaller pressure losses f as compared with ComparativeExamples.

Further, with reference to Tables 1 and 2 as well as FIG. 8, the ratiosf/j of the pressure loss f to the heat transfer coefficient j arecompared between examples having the same end-to-end distance of thehigh heat transfer channel part among E1 to E4 of Examples 1 to 4 and R2to R5 of Comparative Examples 2 to 5. Then, it is clear that Exampleshad significantly smaller ratios f/j as compared with ComparativeExamples.

What is described above clarifies the following: in a case where theparts including the low temperature ends of the effective areas are highheat transfer channel parts (wavy type channels) as is the case withExamples, the pressure loss increases as compared with a case where nohigh heat transfer channel part is provided in the effective areas; butexcellent heat transfer performance can be achieved, while the amplitudeof the increase in the pressure loss can be reduced, as compared with acase where a part of the effective area having a distance equal to theend-to-end distance of the high heat transfer channel part from the hightemperature end of the effective area is the high heat transfer channelpart (wavy type channel), as is the case with each Comparative Example.

Further, a reference line S illustrated in FIG. 8 is a straight lineextended between the point of R1 of Comparative Example 1 and the pointof R6 of Comparative Example 6, and this line can be used as a referencefor determining whether or not the disadvantage of the increase in thepressure loss in the effective area 24 exceeds the advantage of theincrease in the heat transfer coefficient for the effective area 24,which is achieved by the increase in the end-to-end distance of the highheat transfer channel part 26. More specifically, in a case where thepoint specified by the relationship between the end-to-end distance ofthe high heat transfer channel part 26 and the above-described ratio f/jis positioned in a range below the reference line S, this indicates thatthe disadvantage of the increase in the pressure loss in the effectivearea 24 does not exceed the advantage of the increase in the heattransfer coefficient for the effective area 24. Since a comprehensiveheat transfer coefficient, which is a factor for determining the size ofthe heat exchanger 1, is determined according to the film coefficient ofheat transfer in the first channel 21 of the first fluid flowing throughthe first channel 21 and the film coefficient of heat transfer in thesecond channel 22 of the second fluid flowing through the second channel22, the comprehensive heat transfer coefficient of the heat exchanger 1can be improved by the increase in the film coefficient of heat transferof the first fluid in the effective area 24, and to this extent, theheat exchanger 1 can be made compact.

In a case where the point specified by the relationship between theend-to-end distance of the high heat transfer channel part 26 and theabove-described ratio f/j is positioned in a range above the referenceline S, this indicates that the disadvantage of the increase in thepressure loss in the effective area 24 exceeds the advantage of theincrease in the heat transfer coefficient for the effective area 24. Therange below the reference line S corresponds to the range defined by therelational expression (1), and the tilt of this reference line Scorresponds to the value of A in the relational expression (1).

According to FIG. 8, E1 to E4 of Examples 1 to 4 are positioned in therange below the reference line S, and it is therefore clear that in thecases of E1 to E4 of Examples 1 to 4, the disadvantage of the increasein the pressure loss in the effective area 24 does not exceed theadvantage of the increase in the heat transfer coefficient for theeffective area 24, which indicates that the relationship satisfies theabove-described expression (1). On the other hand, R2 to R5 ofComparative Examples 2 to 5 are positioned in the range above thereference line S, and it is therefore clear that in the cases of R2 toR5 of Comparative Examples 2 to 5, the disadvantage of the increase inthe pressure loss in the effective area 24 exceeds the advantage of theincrease in the heat transfer coefficient for the effective area 24,which indicates that the relationship does not satisfy theabove-described relational expression (1).

Further, in a heat exchanger, a pressure loss in a channel is a veryimportant factor in view of practical application. For example, acompressor for compressing fluid is included in a supply device forsupplying fluid to a channel of a heat exchanger in some cases, and whenin such a case the pressure loss in the channels of the heat exchangerincreases, it becomes necessary to boost the pressure of the fluidsupplied to the channels, which causes the power of the compressornecessary for boosting the pressure of the fluid to increase, whichresults in an increase in the energy consumption. Even if providing highheat transfer channel parts in channels inevitably results in anincrease in pressure loss, therefore, it is important to reduce theamplitude of the increase. In a case where providing high heat transferchannel parts in the effective areas of the first channels causes thepressure loss in the effective areas to increase to twice or more thevalue of pressure loss in a case where the entire effective areas arestraight channels, such first channels cannot be used in view ofpractical application of the heat exchanger.

As is clear from Table 1, in Examples 1 to 3 among Examples 1 to 4, thepressure loss f can be suppressed to less than 200, which is a valuetwice the pressure loss f of Comparative Example 1. It is thereforeclear that, in a case where the end-to-end distance of the high heattransfer channel parts including the low temperature ends of theeffective area is 60% or less of the end-to-end distance of theeffective areas, the first channels are sufficiently able to be adoptedfor practical application, in view of pressure loss.

The heat exchanger according to the present invention is not necessarilylimited to a heat exchanger according to the above-described embodiment.As a configuration of the heat exchanger according to the presentinvention, the following configuration, for example, can be adopted.

As a bent channel shape of the high heat transfer channel part, forexample, a corrugated shape formed with continuous curves, such as asine curve, may be used. Further, corners of a zig-zag shape of the highheat transfer channel part do not have to be rounded, but may beangular.

Further, the lengths of the first straight part and the second straightpart of the high heat transfer channel part in the above-describedembodiment, and the tilt angle D formed between the first straight partor the second straight part and the wavy type center line, can be setappropriately. More specifically, the lengths and/or the tilt angle D ofthe first and second straight parts may be by appropriatelyincreased/decreased, and thereby the amplitude of the zig-zag of thehigh heat transfer channel part or the repetition period of zig-zagthereof may be appropriately changed. Further, the curvature of therounded corner parts may be appropriately changed.

Still further, the channel shape of the standard heat transfer channelpart is not limited to the straight shape, and may be any one as long asthe channel shape is such that the channel length of the standard heattransfer channel part per unit distance of the end-to-end distance(straight distance) thereof is smaller than the channel length of thehigh heat transfer channel part per unit distance of the end-to-enddistance thereof. For example, the channel shape of the standard heattransfer channel part may be a gradually curved shape or the like.

Still further, the second channel does not necessarily have a meandershape, and the overall shape thereof may be a straight channel shape oranother channel shape, for example.

Still further, the fluids flowing through the channels in the heatexchanger are necessarily limited to two types of fluids, i.e., thefirst fluid and the second fluid. More specifically, three or more typesof the fluids may be caused to flow through respective channels in theheat exchanger, so that heat exchange occurs among the fluids.

Still further, the configuration of the fluid is not necessarily limitedto a configuration in which the first fluid flowing through the firstchannels is a low temperature fluid and the second fluid flowing throughthe second channels is a high temperature fluid. More specifically, afirst fluid having a high temperature may be caused to flow through thefirst channels, and a second fluid having a low temperature may becaused to flow through the second channels. For example, such a heatexchange method may be performed that in order to lower the temperatureof the first fluid, heat exchange is performed between the first fluidand a refrigerant as a second fluid having a temperature lower than thatof the first fluid.

In this case, the first discharge header 5 is used as a first supplyheader to which a supply pipe for supplying the first fluid isconnected, and the first supply header 3 is used as a first dischargeheader that receives the first fluid flowing out of the first channels21. Further, the second discharge header 6 is used as a second supplyheader to which a supply pipe for supplying the refrigerant isconnected, and the second supply header 4 is used as a second dischargeheader for receiving the refrigerant flowing out of the second channels22. Still further, in this case, the introduction ports 21 a of thefirst channels 21 serve as outflow ports through which the first fluidis allowed to flow out, and the outflow ports 21 b of the first channels21 serve as introduction ports through which the first fluid isintroduced. Still further, the introduction ports 22 a of the secondchannels 22 serve as outflow ports through which the second fluid isallowed to flow out, and the outflow ports 22 b of the second channels22 serve as introduction ports through which the second fluid isintroduced.

Then, the first fluid is supplied through the supply pipe to the firstsupply header and then the first fluid is supplied from the first supplyheader to each first channel 21, whereby, to each first channel 21, thefirst fluid is caused to flow from the standard heat transfer channelpart 25 toward the high heat transfer channel part 26. In other words,the first fluid is caused to flow through each first channel 21 in anorientation opposite to the orientation in the case of theabove-described embodiment. On the other hand, the refrigerant as thesecond fluid is supplied through the supply pipe to the second supplyheader, and then is supplied from the second supply header to eachsecond channel 22, whereby the refrigerant is caused to flow througheach second channel 22 in an orientation opposite to the orientation inwhich the second fluid is caused to flow in the above-describedembodiment. This causes heat exchange to occur between the first fluidflowing through the first channels 21 and the refrigerant flowingthrough the second channels 22, thereby to lower the temperature of thefirst fluid.

-   1 Heat exchanger-   2 Channel structure-   11 First substrate (first layer)-   12 Second substrate (second layer)-   21 First channel-   22 Second channel-   24 Effective area-   24 a High temperature end-   24 b Low temperature end-   25 Standard heat transfer channel part-   26 High heat transfer channel part-   27 Meander center line

What is claimed is:
 1. A heat exchanger that causes a plurality offluids to flow therethrough so as to cause heat exchange to occurbetween the fluids, the heat exchanger comprising a channel structurethat includes: a first layer in which a first channel that is amicrochannel through which one fluid is caused to flow is arrayed; and asecond layer stacked on the first layer, in which a second channel thatis a microchannel through which another fluid is caused to flow isarrayed, the other fluid being a fluid different from the one fluid,wherein the first channel has an effective area that overlaps a rangewhere the second channel in the second layer is provided, when viewed ina direction in which the first layer and the second layer are stacked,wherein the effective area includes: a standard heat transfer channelpart that includes a high temperature end that is one of ends of theeffective area; and a high heat transfer channel part that is equivalentto a part of the effective area other than the standard heat transferchannel part, the high heat transfer channel part including a lowtemperature end that is an end of the effective area on a side oppositeto the high temperature end and through which the one fluid having atemperature lower than a temperature of the one fluid flowing at thehigh temperature end, and wherein the high heat transfer channel parthas a channel shape bent in such a manner that a channel length thereofper unit distance of an end-to-end distance thereof is greater than achannel length of the standard heat transfer channel part per unitdistance of an end-to-end distance thereof.
 2. The heat exchangeraccording to claim 1, wherein the standard heat transfer channel part isa straight channel, and wherein the high heat transfer channel part is awavy type channel.
 3. The heat exchanger according to claim 2, whereinthe high heat transfer channel part meanders in such a manner as beingdeflected to both sides with respect to a center line that is a straightline, and wherein the end-to-end distance of the high heat transferchannel part in a direction along the center line is 60% or less of anend-to-end distance of the effective area.
 4. The heat exchangeraccording to claim 3, wherein the end-to-end distance of the high heattransfer channel part in a direction along the center line is 10% ormore of the end-to-end distance of the effective area.
 5. The heatexchanger according to claim 2, wherein the high heat transfer channelpart meanders in such a manner as being deflected to both sides withrespect to a center line that is a straight line, and wherein theend-to-end distance of the high heat transfer channel part in adirection along the center line is smaller than the end-to-end distanceof the standard heat transfer channel part.
 6. A heat exchange methodcomprising: causing one fluid to flow through the first channel in theheat exchanger according to claim 1 from the standard heat transferchannel part toward the high heat transfer channel part, and at the sametime, causing a refrigerant as another fluid to flow through the secondchannel in the heat exchanger, so as to cause heat exchange to occurbetween the one fluid and the refrigerant.
 7. A heat exchange methodcomprising: causing one fluid to flow through the first channel in theheat exchanger according to claim 1 from the high heat transfer channelpart toward the standard heat transfer channel part, and at the sametime, causing a hot medium as another fluid to flow through the secondchannel in the heat exchanger, so as to cause heat exchange to occurbetween the one fluid and the hot medium.